Large walk-in type coolers, such as those commonly found in refrigerated warehouses, are typically constructed with door openings sized to accommodate dollies and forklifts. These coolers have large insulated doors which are suspended from guide rails mounted above the door openings by a pair of trolleys mounted to the top of the door adjacent its sides. The trolleys guide the doors beneath the rails in a sideways direction and thus are referred to as sliding doors.
To insure a tight seal between the cooler door and door jamb, and between the cooler door and the underlying floor, resilient, sealing strips are provided therebetween. However, were the door to be slid across rather than brought into abutment with the sealing strips, the strips would quickly wear. To avoid this substantial sliding contact with the sealing strips, the cooler door is guided away from the door jambs and upward from the floor upon initial opening, and vice versa upon final closing. This is accomplished by providing the guide rail with deviation ramp portions which simultaneously direct the trolleys thereon, and hence the door, in these directions. However, a problem with these ramps has been that the trailing trolley, i.e. the trolley adjacent the trailing edge of the door as it is slid open, has passed over and therefore rode down the deviation rail ramp portion which directs the leading trolley for sealing and unsealing as the door is slid closed and open. This may cause the bottom trailing corner of the door to strike the floor and place substantial stress upon the system at this point.
To prevent the just described problem from occurring the trolleys have had to be mounted outboard of the door so that they do not reach the deviation rail portion for the leading trolley during door travel. This however in turn requires that the rail extend beyond the door jamb. Also, this is not feasible with coolers having double doors which slide into abutment with each other upon closing since such outboard trolleys would make contact with each other prior to the doors moving into mutual abutment.
It thus is seen that a need remains for a trolley rail system having guide ramps for supporting and guiding a sliding door between a closed position and an open position without causing wear to sealing strips and which does not require the use of outboard trolleys. Accordingly, it is to the provision of such that the present invention is primarily directed.